This is the first global map of ocean surface topography produced with
data from the new interleaved tandem mission of the Jason-1 and Ocean
Surface Topography Mission (OSTM)/Jason-2 satellites.
In January 2009, Jason-1 was maneuvered into orbit on the opposite side of
Earth from its successor, OSTM/Jason-2 satellite. It takes 10 days for the
satellites to cover the globe and return to any one place over the ocean.
So, in this new tandem configuration, Jason-1 flies over the same region
of the ocean that OSTM/Jason-2 flew over five days earlier. Its ground
tracks fall mid-way between those of Jason-2, which are about 315
kilometers (195 miles) apart at the equator.
Working together, the two spacecraft measure the surface topography of the
ocean twice as often as would be possible with one satellite, and over a
10-day period, they return twice the amount of detailed measurements.
Combining data from the two satellites makes it possible to map smaller,
more rapidly changing features than one satellite could alone.
This image shows sea-level anomaly data from the first 14 days of the
interleaved orbit of Jason-1 and OSTM/Jason-2, the period beginning on
Feb. 20, 2009. An anomaly is a departure from a value averaged over a long
period of time.
Red and yellow are regions where sea levels are higher than normal. Purple
and dark blue show where sea levels are lower. A higher-than-normal sea
surface is usually a sign of warm waters below, while lower sea levels
indicate cooler than normal temperatures. The small-sized patches of highs
and lows are ocean eddies, the storms of ocean weather that carry most of
the energy of ocean circulation. These are not well observed with only one
satellite.
Jason-1 is a joint mission of NASA and the French space agency, CNES. The
U.S. portion of the Jason-1 mission is managed by JPL for NASA's Science
Mission Directorate, Washington, D.C.
OSTM/Jason 2 is an international endeavor with responsibility for
satellite development and launch shared between NASA and CNES. The U.S.
National Oceanic and Atmospheric Administration (NOAA) is responsible for
satellite operations, and JPL is managing the mission for NASA. Data
processing is being carried out by CNES, the European Organisation for the
Exploitation of Meteorological Satellites (EUMETSAT) and NOAA.